Raman of Nano-objects at subwavelength scales

Our group develops an original approach combining an Atomic Force Microscope and a confocal-Raman microscope, where AFM microscope is used either to image and to manipulate nano-particles under the confocal optical microscope... [ view full abstract ]

Our group develops an original approach combining an Atomic Force Microscope and a confocal-Raman microscope, where AFM microscope is used either to image and to manipulate nano-particles under the confocal optical microscope coupled at the Raman spectrometer or to enhance local electric field by plasmonic effects. Moreover, our optical device allows us to scan the resonance effects by tuning the wavelengths of excitation.

This presentation will show the results obtained with some symmetric structures of assembling of metallic nano-particles, in the vicinity of a single and isolated nanoobject. We will investigate the consequence on the spatial super-resolved Raman spectra and as a function of the different sub-wavelength-scale geometries of aggregates. We will discuss the different interactions between nano-particles, including their impact on resonance effects. In particular, we will focus on the enhancement of the local electrical field by metallic nano-structures to probe single objects. These experimental data are interpreted according to finite element models of far and local electromagnetic fields. Thus, on one hand, we achieve to a better understanding about the tunability of plasmon resonance modes of home-tailored nanostructures, including sensitive breaks symmetry modes. On the other hand, the consequences of their interactions with a substrate or molecule dipole moment, depending on the excitation wavelength (especially in the case of the inelastic scattering), are studied. All this allows us to understand and predict the experimental observation